Complexes of the general formula[MXH
2(dppp)
2]
n+(M = Ru, Os; X = H, Cl, CO; dppp = 1,3-bis(diphenylphosphino)propane) have been prepared and characterized,and the effect of the donor/acceptor propertiesof X on their structure and acidity has been studied. Thefive-coordinate complexes[MCl(dppp)
2]
+ (M = Ru(
1a), Os (
1b)) react with H
2 gas inCH
2Cl
2 to give the complexes[MCl(
2-H
2)(dppp)
2]
+(M = Ru (
2a), Os (
2b))containing elongated dihydrogen ligands. The molecular structureof
2b has been determined by X-raycrystallography (monoclinic, space group
P2
1/
n with
a =13.314(7) Å,
b = 18.63(2) Å,
c =23.20(2) Å,
![](/images/gifchars/beta2.gif)
=94.58(6)
![](/images/entities/deg.gif)
, and
Z = 4). Chlorohydride[OsH(Cl)(dppp)
2] (
3b) reacts withH
2 gas in the presence ofNa[BPh
4]forming [OsH
3(dppp)
2]
+(
4b). Protonation of[OsH
2(dppp)
2] (
5b) withHBF
4·Et
2O also gives
4b.A combinationof X-ray crystallography (monoclinic, space group
P2
1/
n with
a =13.392(3) Å,
b = 25.306(7) Å,
c =21.247(7)Å,
![](/images/gifchars/beta2.gif)
= 91.15(2)
![](/images/entities/deg.gif)
, and
Z = 4) and
1H and
31P NMR studies indicate that
4b is a classical trihydride.Hydridocarbonyls[MH(CO)(dppp)
2]
+ (M = Ru(
6a), Os (
6b)) are protonated byF
3CSO
3H inCD
2Cl
2 to yield[M(CO)(
2-H
2)(dppp)
2]
2+(M = Ru (
7a), Os (
7b)), which werecharacterized in solution.
7a is stable onlyatlow temperature. Compound
7b is a highly acidicdihydrogen complex with an estimated p
Ka of-6.